The goal of this research has been, and continues to be, the development of new ultrasonic tools for the characterization and separation of biomaterials. These tools are possible because of the observation that an object in an ultrasonic field moves in response to differences in its elastic modulus and density from the surrounding fluid. The ability to separate by elastic property, if developed sufficiently, would offer a new dimension to the technology of separation, complementing such tools as the centrifuge which are based on density differences. One of the first materials to which our ultrasonic science has been applied is blood. When the ultrasonic transducer is turned on, an acoustic standing wave is established in an isotonic solution containing red blood cells (rbc's). Within a few seconds the rbc's will form narrow red bands. The position of these bands on the column of solution helps to determine the physical properties of the red blood cell. In instances in which different bio-materials are in solution, the sound field will cause the materials to separate spatially in the column. The determination of degree to which physical characterization and separation can be achieved is one of the primary objectives of this project.